you could ask the 
Hive account@blocktivity account on STEEM if he would also include HIVE into the list. I don't know any other source that is counting up the daily transactions.
HIVE transactions technically cannot really drop as there is not even a 7-day average yet, to compare it to.
RE: Steem transaction volume already crashed by 90%, we are only 2 days into HIVE!